Recipe for 2 persons.

Preheat the oven to 190 °C. Clean and peel the potatoes and the onion.
In this simple recipe, we sauté the shredded potatoes first, then finish them in the oven. The result is an extra-crispy outer layer with a soft, buttery center. You can mix in extra ingredients with the potatoes for different variations.
Grate the potatoes and the onion with a food processor. You can also grate it by hand, but it takes longer.
Plunge the shredded potato into cold water and rinse away excess starch. Drain away excess water with paper towels.
Melt a knob of butter in a large (25 cm) nonstick frying pan over medium-high heat.
Add prepared potato to the hot pan. Press the potato shreds flat so that that they cover the bottom of the pan.
Cook for about 5 minutes, or until the bottom surface becomes golden and crisp. And turn by a simple plate trick. Put on 1 plate, then cover with another plate, and turn the plates upside down. When ready move the pan into the oven (or when the pan is not made for the oven, put the rosti on a baking sheet covered baking tray.

Bake for around 10–15 minutes. Remove the pan from the oven, and then carefully flip the rösti. Bake for another 15 minutes.
NOTE: The baking time is never the same when using an other oven. So make sure that when the top of the rösti begins to turn lightly golden, it’s time to flip the potatoes. The finished rösti should be golden brown on both sides.
After baking the rösti, let it rest for 5 minutes. As the surface cools, it will become crisper.
Season with salt and pepper to taste.

You can eat it just like that as a side dish. Or you can eat as we did, with pulled smoked salmon, parsley and a sunny side up.